911 research outputs found
Negative exponential behavior of image mutual information for pseudo-thermal light ghost imaging: Observation, modeling, and verification
When use the image mutual information to assess the quality of reconstructed
image in pseudo-thermal light ghost imaging, a negative exponential behavior
with respect to the measurement number is observed. Based on information theory
and a few simple and verifiable assumptions, semi-quantitative model of image
mutual information under varying measurement numbers is established. It is the
Gaussian characteristics of the bucket detector output probability distribution
that leads to this negative exponential behavior. Designed experiments verify
the model.Comment: 13 pages, 6 figure
Binary sampling ghost imaging: add random noise to fight quantization caused image quality decline
When the sampling data of ghost imaging is recorded with less bits, i.e.,
experiencing quantization, decline of image quality is observed. The less bits
used, the worse image one gets. Dithering, which adds suitable random noise to
the raw data before quantization, is proved to be capable of compensating image
quality decline effectively, even for the extreme binary sampling case. A brief
explanation and parameter optimization of dithering are given.Comment: 8 pages, 7 figure
Molecular dynamics investigation of interfacial adhesion between oxidised bitumen and mineral surfaces
The interfacial adhesion between oxidised bitumen and mineral surfaces at dry and wet conditions was investigated using molecular dynamics (MD) simulations. Molecular models were built for virgin and oxidised bitumen components including saturate, aromatic, resin and asphaltenes. The bitumen models and four representative mineral substrates (namely quartz, calcite, albite and microcline) were employed to construct bitumen-mineral interface systems. These models were validated by the experimental results and MD simulations reported in the literature. The hardening mechanism of the aged bitumen was analysed by comparing the density, cohesive energy density and fraction of free volume between the virgin and oxidised bitumen. Work of adhesion was computed to quantify the adhesive bonding property of the bitumen-mineral interface systems for the virgin, lightly oxidised and heavily oxidised bitumen models under dry and wet conditions. Results show that the oxidised products (carbonyl and sulfoxide) strengthen the intermolecular bonding, resulting in molecular aggregation and physical hardening of the aged bitumen. When bitumen becomes oxidised at the dry condition, the interfacial adhesion of bitumen-acidic minerals (quartz) is dominated by van der Waals interaction which decreases due to the increased bitumen-quartz intermolecular distance caused by the aggregated bitumen molecules during aging. In comparison, the interfacial adhesion of bitumen-strong alkali minerals (albite and microcline) is dominated by electrostatic energy which increases due to higher polarity introduced by the oxidised products. For the bitumen-weak alkali mineral (calcite), the interfacial adhesion is attributed to both electrostatic energy and van der Waals energy, where compared to the virgin bitumen, the electrostatic energy becomes lower for the lightly-oxidised bitumen due to the increased bitumen-mineral distance but becomes higher for the heavily-oxidised bitumen due to higher polarity. At wet condition, water is the dominating factor that affects (weakens) the interfacial adhesion between the bitumen and the acidic minerals (quartz), and the oxidative aging of bitumen is the major factor that affects (strengthens) the interfacial adhesion between the bitumen and the strongly alkaline minerals (albite and microcline). For the weak alkali minerals such as calcite, both water and bitumen aging can significantly affect the interfacial adhesion
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